Computer with force sensing resistor

ABSTRACT

A computer includes a motherboard with a signal receiving port and a switch circuit. The switch circuit includes a force sensing module and a transistor. The transistor includes a first terminal connected to the force sensing module, a second terminal connected to a power source, and a third terminal connected to the signal receiving port. When there is a pressure applied to the force sensing module, the force sensing module outputs a first driving signal to turn on the transistor and enables the computer to maintain its current power on or off state. When there is no pressure applied to the force sensing module, the force sensing module outputs a second driving signal to turn off the transistor and switches on or off the computer.

BACKGROUND

1. Technical Field

The present disclosure relates to a computer with a force sensingresistor.

2. Description of Related Art

A computer may be turned on or off by pressing a power button installedon a front panel of the computer. The power button may include a movableportion and a resilient member. The movable portion can be pressed byusers to turn on or off the computer. The resilient member is able tourge the movable portion to return to its original position. However,the power button has a complicate mechanical structure, which may occupymuch space of the computer.

Therefore, there is room for improvement within the art.

BRIEF DESCRIPTION OF THE DRAWINGS

Many aspects of the embodiments can be better understood with referenceto the following drawings. The components in the drawings are notnecessarily drawn to scale, the emphasis instead being placed uponclearly illustrating the principles of the embodiments. Moreover, in thedrawings, like reference numerals designate corresponding partsthroughout the several views.

FIG. 1 illustrates a block diagram of a computer in accordance with anembodiment.

FIG. 2 illustrates a switch circuit of the computer of FIG. 1 inaccordance with one embodiment.

FIG. 3 illustrates a switch circuit of the computer of FIG. 1 inaccordance with another embodiment.

DETAILED DESCRIPTION

The disclosure is illustrated by way of example and not by way oflimitation. In the figures of the accompanying drawings, like referencesindicate similar elements. It should be noted that references to “an” or“one” embodiment in this disclosure are not necessarily to the sameembodiment, and such references mean at least one.

Referring to FIG. 1, an embodiment of a computer 10 is shown. Thecomputer 10 includes a switch circuit 20 and a motherboard 30 connectedto the switch circuit 20. The switch circuit 20 outputs apower-button-press (PWRBTN#) signal to the motherboard 30 for switchingon or off the computer 10.

FIG. 2 shows in one embodiment of the switch circuit 20. The switchcircuit 20 includes a first force sensing module 40. The first forcesensing module 40 includes a first resistor R1 and a first force sensingresistor FSR_1. A first end of the first resistor R1 is coupled to a3.3V power source. A second end of the first resistor R1 is connected toa first node A. A first end of the first force sensing resistor FSR_1 isconnected to the first node A. A second end of the first force sensingresistor FSR_1 is connected to ground. The switch circuit 20 furthercomprises a first transistor Q1 and a second resistor R2. A baseterminal of the first transistor Q1 is connected to the first node A. Acollector terminal of the first transistor Q1 is coupled to the 3.3Vpower source. An emitter terminal of the first transistor Q1 isconnected to a second node B. A first end of the second resistor R2 isconnected to the second node B. A second end of the second resistor R2is connected to ground. The second node B is connected to a PWRBTN# port32 of the motherboard 30. In one embodiment, the first transistor Q1 isan NPN type bipolar transistor.

The first force sensing resistor FSR_1 can be mounted into a chassis ofthe computer 10. A power button label can be put on the chassis andlocated above the first force sensing resistor FSR_1. When the firstforce sensing resistor FSR_1 is not pressed by user and the first forcesensing resistor FSR_1 is in an original state, a resistance of thefirst force sensing resistor FSR_1 is much greater than that of thefirst resistor R1. A voltage at the first node A is at high level (logic1). The first transistor Q1 is switched on. A voltage at the second nodeB is at logic 1. Thus, the PWRBTN# signal is at logic 1 and the computer10 maintains a current power on or off state. When the first forcesensing resistor FSR_1 is pressed by user, the resistance of the firstforce sensing resistor FSR_1 decreases and becomes less than that of thefirst resistor R1. The voltage at the first node A is pulled to lowlevel (logic 0). The first transistor Q1 is switched off. The voltage atthe second node B is at logic 0. Thus, the PWRBTN# signal is at logic 0and the computer 10 is switched on or off.

Referring to FIG. 3, in another embodiment, the switch circuit 20includes a second force sensing module 40A. The second force sensingmodule 40A includes a second force sensing resistor FSR_2, a thirdresistor R3, and an amplifier 50. A first end of the second forcesensing resistor FSR_2 is coupled to a 3.3V power source. A second endof the second force sensing resistor FSR_2 is connected to a third nodeC. A first end of the third resistor R3 is connected to the node C. Asecond end of the third resistor R3 is connected to ground. A positiveinput terminal of the amplifier 50 is connected to the third node C. Anegative input terminal of the amplifier 50 is connected to an outputterminal of the amplifier 50. The switch circuit 20 further includes asecond transistor Q2 and a fourth resistor R4. A base terminal of thesecond transistor Q2 is connected to the output terminal of theamplifier 50. A collector terminal of the second transistor Q2 isconnected to the 3.3V power source. An emitter terminal of the secondtransistor Q2 is connected to a fourth node D. A first end of the fourthresistor R4 is connected to the fourth node D. A second end of thefourth resistor R4 is connected to ground. The fourth node D isconnected to the PWRBTN# port 32 of the motherboard 30.

The amplifier 50 functions as a buffer in the switch circuit. A voltageon the positive terminal of the amplifier 50 is equal to that on theoutput terminal of the amplifier 50. When the second force sensingresistor FSR_2 is not pressed by a user, a resistance of the secondforce sensing resistor FSR_2 is much greater than that of the thirdresistor R3. A voltage at the third node C is at logic 0. The outputterminal of the amplifier 50 is at logic 0. The second transistor Q2 isswitched on. A voltage at the fourth node D is at logic 1. Thus, thePWRBTN# signal is at logic 1 and the computer 10 maintains a currentpower on or off state. When second first force sensing resistor FSR_2 ispressed by user, the resistance of the second force sensing resistorFSR_2 decreases and becomes less than that of the third resistor R3. Thevoltage at the third node C is pulled up to logic 1. The output terminalof the amplifier is at logic 1. The second transistor Q2 is switchedoff. The voltage at the fourth node D is at logic 0. Thus, the PWRBTN#signal is at logic 0 and the computer 10 is switched on or off.

In above embodiments, the first transistor Q1 and the second transistorQ2 function as switches which can be replaced by other transistors, suchas field-effect transistors. Other force sensors can also replace theforce sensing resistors.

While the present disclosure has been illustrated by the description inthis embodiment, and while the embodiment has been described inconsiderable detail, it is not intended to restrict or in any way limitthe scope of the appended claims to such details. Additional advantagesand modifications within the spirit and scope of the present disclosurewill readily appear to those skilled in the art. Therefore, the presentdisclosure is not limited to the specific details and illustrativeexamples shown and described.

What is claimed is:
 1. A computer comprising: a motherboard with asignal receiving port; a switch circuit comprising a force sensingmodule and a transistor, the transistor comprises a first terminalconnected to the force sensing module, a second terminal connected to apower source, and a third terminal connected to the signal receivingport; wherein when no pressure is applied to the force sensing module,the force sensing module outputs a first driving signal to turn on thetransistor, and the third terminal sends a first signal to the signalreceiving port to keep a power on or off state of the computerunchanged; and when a pressure is applied to the force sensing module,the force sensing module outputs a second driving signal to turn off thetransistor, and the third terminal sends a second signal to the signalreceiving port to switch off or on the computer accordingly; wherein theforce sensing module comprises a force sensing resistor of which aresistance decreases when there is a pressure applied thereto, the forcesensing module further comprises an amplifier connected between theforce sensing resistor and the transistor and a third resistor, which isconnected to the force sensing resistor in series, a positive inputterminal of the amplifier is connected to a third node, a negative inputterminal of the amplifier is connected to an output terminal of theamplifier, a first end of the force sensing resistor is connected to thepower source, and a second end of the force sensing resistor isconnected to the third node; the first terminal of the transistor isconnected to the output terminal of the amplifier; a first end of thethird resistor is connected to the third node, and a second end of thethird resistor is grounded.
 2. The computer of claim 1, wherein theforce sensing module further comprises a first resistor, a first end ofthe first resistor is connected to the power source, and a second end ofthe first resistor is connected to a first node, the first terminal isconnected to the first node; a first end of the force sensing resistoris connected to the first node, and a second end of the force sensingresistor is connected to ground.
 3. The computer of claim 2, wherein thetransistor is an NPN type bipolar transistor, the first terminal is abase terminal, the second terminal is a collector terminal, and thethird terminal is an emitter terminal.
 4. The computer of claim 3,wherein the switch circuit further comprises a second resistor, a firstend of the second resistor is connected to the emitter terminal, and asecond end of the second resistor is connected to ground.
 5. Thecomputer of claim 1, wherein the transistor is a PNP type bipolartransistor, the first terminal is a base terminal, the second terminalis a collector terminal, and the third terminal is an emitter terminal.6. The computer of claim 5, wherein the switch circuit further comprisesa fourth resistor, a first end of the fourth resistor is connected tothe emitter terminal, and a second end of the fourth resistor isconnected to ground.
 7. The computer of claim 1, wherein the firstsignal is at high level, the second signal is at low level, and a levelof the first driving signal is opposite to that of the second drivingsignal.
 8. A computer, comprising a circuit, the circuit comprises: aforce sensing module comprising a force sensor and a first resistorconnected to the force sensor in series, each of the force sensor andthe first resistor connected to a node; and a transistor comprising afirst terminal connected to the node, a second terminal connected to apower source, and a third terminal connected to ground via a secondresistor, the third terminal used to send a PWRBTN signal to switch ormaintain a power on or off state of the computer; wherein when nopressure is applied to the force sensor, the force sensing moduleoutputs a first driving signal to turn on the transistor, and the thirdterminal sends a first PWRBTN signal to keep a power on or off state ofthe computer unchanged; when there is a pressure applied to the forcesensor, the force sensing module outputs a second driving signal to turnoff the transistor, and the third terminal sends a second PWRBTN signalto switch off or on the computer; wherein the force sensor is a forcesensing resistor of which a resistance decreases when there is apressure applied thereto, a first end of the force sensing resistor isconnected to the power source, and a second end of the force sensingresistor is connected to the node; a first end of the first resistor isconnected to the node, and a second end of the first resistor isconnected to ground, the force sensing module further comprises anamplifier connected between the force sensing resistor and thetransistor, a positive input terminal of the amplifier is connected tothe node, a negative input terminal of the amplifier is connected to anoutput terminal of the amplifier, the first terminal of the transistoris connected to the output terminal of the amplifier.
 9. The circuit ofclaim 8, wherein a first end of the first resistor is connected to thepower source, and a second end of the first resistor is connected to thenode; a first end of the force sensing resistor is connected to thenode, and a second end of the force sensing resistor is connected toground.
 10. The circuit of claim 9, wherein the transistor is an NPNtype bipolar transistor, the first terminal is a base terminal, thesecond terminal is a collector terminal, and the third terminal is anemitter terminal.
 11. The circuit of claim 8, wherein the transistor isa PNP type bipolar transistor, the first terminal is a base terminal,the second terminal is a collector terminal, and the third terminal isan emitter terminal.
 12. The circuit of claim 8, wherein the firstPWRBTN signal is at high level, the second PWRBTN signal is at lowlevel, and a level of the first driving signal is opposite to that ofthe second driving signal.